The present invention relates to a method of forming complex features and fine details in work pieces made of Carbonxe2x80x94Carbon composite material and other carbon-containing materials. The present invention also relates to heat exchangers and fuel cells.
Carbonxe2x80x94Carbon composite materials are used in certain heat exchangers. Consider a Carbonxe2x80x94Carbon plate-fin heat exchanger core including a stack of plates and fins. The plates may be made from flat thin-gauge two-dimensional Carbonxe2x80x94Carbon woven fabrics, and the fins may be made from thin-gauge two-dimensional Carbonxe2x80x94Carbon woven fabrics that are corrugated. Thickness of the plates and fins may range between 0.1 millimeters and 1 millimeter.
Fabricating the Carbonxe2x80x94Carbon fins is difficult. The fins define long, narrow channels that function as fluid passageways. Shapes are complex. Creating a high density of fins (i.e., x number of fins per linear inch) is even more difficult. Yet it is extremely desirable to increase the fin density. Increasing the fin density increases the heat transfer capability.
Carbonxe2x80x94Carbon composite materials are used in certain fuel cells. Carbonxe2x80x94Carbon bipolar plates of proton exchange membrane fuel cells are typically flat, have a thickness of 0.2-1 millimeters and, in addition, have intricately shaped, fine-featured flow fields for channeling the flow of the hydrogen and oxygen gases used in the operation of the fuel cells. These flow fields typically have features of sub-millimeter dimensions. Forming such fine details is extremely difficult.
Complex shapes and fine details in a carbon-containing work piece are formed by electrical discharge machining. An electrode used in the machining is made of a material that is mechanically and chemically compatible with the carbon-containing work piece.